CN114347966B

CN114347966B - Electromechanical brake device and control method thereof

Info

Publication number: CN114347966B
Application number: CN202111194514.1A
Authority: CN
Inventors: 金钟圣
Original assignee: Hyundai Mobis Co Ltd
Current assignee: Hyundai Mobis Co Ltd
Priority date: 2020-10-13
Filing date: 2021-10-13
Publication date: 2023-11-28
Anticipated expiration: 2041-10-13
Also published as: CN114347966A; KR20220048877A; US20220111824A1

Abstract

A control method of an electromechanical brake apparatus, comprising: switching a central Electronic Control Unit (ECU) to a wake mode based on the wake signal; transmitting a signal to cause the wheel ECU to switch from the sleep mode to the wake mode; when a brake input is detected, current is supplied to a motor mounted on an electromechanical brake (EMB) using current control to generate a braking force; when the parking braking force is smaller than the required braking force, controlling the wheel ECU to release the parking braking force and generate the required braking force, and when the parking braking force is greater than or equal to the required braking force, releasing the parking braking force and maintaining the braking force generated by the wheels; when the braking force reaches the required braking force or the braking force is maintained, the current control is switched to the position control.

Description

Electromechanical brake device and control method thereof

Technical Field

Embodiments of the present disclosure relate to an electromechanical braking device and a control method thereof.

Background

The matters described in this section merely provide background information of the present disclosure and do not constitute related art.

Electromechanical brakes (EMB) have been developed and widely used. Although the EMB has been developed to be used as an electronic parking brake (Electronic Parking Brake, EPB), in recent years, as the EMB is used for a main brake by replacing a conventional hydraulic brake, its range of use has been expanded. EMB is a device in which an actuator driven by a motor is mounted on a caliper to directly brake a vehicle with a motor driving force without using a medium such as brake fluid. EMB has a similar mechanism to EPB, but unlike EPB, EMB is mainly used for main braking and thus requires higher brake response and running durability than EPB. In addition, the EMB has a simpler structure, a faster brake response speed, and can be controlled more precisely than the hydraulic brake, and thus has excellent braking safety.

Meanwhile, when the driver does not get on the vehicle, the central control unit (Central Control Unit, CCU) and the wheel control unit (Wheel Control Unit, WCU) control the EMB to wait in the sleep mode. When the driver gets on the vehicle, the wake-up sensor activates the CCU and WCU in sleep mode using a door open signal, a brake light signal, an ignition signal, or the like.

However, when the wake sensor is connected to the WCU, there are problems in that the number of connector pins included in the WCU increases and the connection structure is complicated.

To overcome the problems of the increase in the number of connector pins and the complexity of the connection structure, when a door opening signal, a brake light signal, an ignition signal, or the like is applied to the CCU and the CCU activates the WCU using the vehicle-mounted communication, the number of connector pins can be reduced and the connection structure can be simplified. However, there is a problem in that the time required to initialize the electronic control unit (Electronic Control Unit, ECU) and the actuator of the EMB increases, and in addition, there is a problem in that delay occurs in the generation of braking force by the EMB.

Disclosure of Invention

The present disclosure is directed to reducing the number of connector pins and simplifying a connection structure by applying a door opening signal, a brake light signal, an ignition signal, or the like to a central electronic control unit according to one embodiment of the present disclosure, and allowing the central electronic control unit to activate the wheel electronic control unit using vehicle-mounted communication.

The present disclosure is also directed to activating a wheel electronic control unit using an on-board communication and simplifying initialization of an electro-mechanical brake (EMB) actuator and minimizing the time required to initialize the EMB such that no delay occurs in the generation of braking force by the EMB.

According to at least one aspect, the present disclosure provides a control method of an electromechanical brake apparatus, the method comprising: a central electronic control unit wake-up operation for switching the central electronic control unit to a wake-up mode based on a wake-up signal received from a wake-up sensor; a wheel electronic control unit wakes up an operation, and causes the wheel electronic control unit to switch from a sleep mode to the wake-up mode using the vehicle-mounted communication transmission signal; a current control operation of supplying current to a motor mounted on the electromechanical brake using current control to generate braking force when a braking input is detected; a comparison operation of comparing the magnitude of the parking braking force with the required braking force based on the braking input; a braking force generation operation of controlling the wheel electronic control unit to release the parking braking force and generate the required braking force when the parking braking force is determined to be less than the required braking force, and to release the parking braking force and maintain the braking force generated by the wheels when the parking braking force has been determined to be greater than or equal to the required braking force; a position control operation of switching the current control to a position control when the braking force reaches the required braking force or the braking force is maintained; and an initializing operation of recognizing a contact point between the brake pad and the disc when a piston mounted on the electromechanical brake is retracted when a braking force release signal is transmitted, and initializing the electromechanical brake.

Drawings

Fig. 1 is a block diagram of an electromechanical braking device according to one embodiment of the present disclosure.

Fig. 2 is a block diagram of an electromechanical braking device for a vehicle according to one embodiment of the present disclosure.

Fig. 3 is a flowchart illustrating an algorithm of a central electronic control unit according to one embodiment of the present disclosure.

Reference numerals

100: sensor unit 112: position sensor

114: current sensor 116: stroke sensor

118: wake-up sensor 120: central electronic control unit

122: the first microcomputer 124: second microcomputer

131: FL controller 132: FR controller

133: RL controller 134: RR controller

140: the brake unit 150: multiple wheel brake units

160: a plurality of batteries 162: first battery

164: second battery

Detailed Description

Some exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description, like reference numerals preferably denote like elements, although these elements are shown in different drawings. In addition, in the following description of some embodiments, a detailed description of known functions and configurations incorporated herein will be omitted for clarity and conciseness.

Furthermore, various terms such as first, second, A, B, (a), (b), and the like, are used solely to distinguish one element from another element, and do not necessarily imply a substance, rule, or order of the elements. In this specification, when a portion "comprises" or "comprising" an element, it is intended that the portion further comprises other elements, unless specifically stated to the contrary, other elements are not excluded. Terms such as "unit," "module," and the like refer to one or more units for processing at least one function or operation, which may be implemented in hardware, software, or a combination thereof.

Referring to fig. 1 and 2, an electromechanical brake apparatus 100 according to one embodiment of the present disclosure includes a sensor unit 110, a central electronic control unit (central ECU) 120, a wheel ECU 130, a brake unit 140, a plurality of wheel brake units 150, and all or some of a plurality of batteries 160.

The sensor unit 110 includes all or some of a position sensor 112, a current sensor 114, a stroke sensor 116, and a wake-up sensor 118.

The position sensor 112 measures the running distance of the motor. Here, the running distance refers to a linear movement distance when a piston (not shown) of an electric brake (EMB) is linearly moved when the motor rotates.

Meanwhile, in order for the EMB to generate braking force, the piston presses a brake pad (not shown). The force with which the piston presses the brake pad is defined as the clamping force.

The current sensor 114 measures the current flowing in the motor.

The stroke sensor 116 detects the stroke strength of a brake pedal (not shown). The braking force release signal may be generated based on the stroke information transmitted by the stroke sensor 116.

The wake sensor 118 is a sensor that detects movement of the driver before the vehicle starts running to activate the central ECU 120. The wake-up sensor 118 may be, for example, a door opening sensor (not shown) that detects whether the driver's door is open and generates a door opening signal and transmits it to the central ECU 120.

Since the door opening sensor is generally installed in a door of a vehicle at a driver seat, the door opening sensor cannot detect whether the driver gets on the vehicle when the driver gets on the vehicle through a passenger seat. Accordingly, the wake-up sensors may also include a brake light sensor (Brake Light Sensor, BLS) (not shown) that detects whether a brake light is on and an ignition sensor (not shown) that detects whether the engine is on.

The sensor unit 110 transmits the detected various information to the central ECU 120.

The central ECU 120 includes a first microcomputer 122 and a second microcomputer 124. The central ECU 120 generates a friction brake signal and a friction brake release signal for controlling the wheel ECU 130.

The central ECU 120 receives power from the plurality of batteries 160. More specifically, the first microcomputer 122 receives power from the first battery 162, and the second microcomputer 124 receives power from the second battery 164.

The central ECU 120 controls EMBs mounted on each of the front and rear wheels to generate braking forces. More specifically, the first microcomputer 122 transmits an electric signal such that the FL controller 131 causes the EMB mounted on the left front wheel to generate a braking force, and the first microcomputer 122 transmits an electric signal such that the RR controller 134 causes the EMB mounted on the right rear wheel to generate a braking force. The FL controller 131 and RR controller 134 that receive the signals control the EMB to provide braking force to the left front wheel and the right rear wheel. Here, the electrical signal is a signal transmitted using vehicle-mounted communication (e.g., controller area network (Controller Area Network, CAN) communication). In addition, the in-vehicle communication may be local area network (Local Area Network, LAN) communication.

The first microcomputer 122 determines whether the vehicle requires braking. Whether the vehicle requires braking, such as the strength of the stroke of the brake pedal, is determined based on various factors. When it is determined that the braking input is required, the first microcomputer 122 calculates a braking force required to brake the vehicle. The first microcomputer 122 controls the brake units 140 such that the plurality of wheel brake units 150 generate the calculated braking force.

Since the second microcomputer 124 performs a function similar to that of the first microcomputer 122, differences from the first microcomputer 122 will be mainly described for convenience of description.

The second microcomputer 124 receives power from the second battery 164.

The process of the second microcomputer 124 determining whether the vehicle needs braking, calculating braking force, and controlling the brake unit 140 follows the same algorithm as the first microcomputer 122. However, the difference is that the first microcomputer 122 brakes the left front wheel and the right rear wheel, and the second microcomputer 124 brakes the right front wheel and the left rear wheel.

The second microcomputer 124 transmits an electric signal such that the FR controller 132 causes the EMB mounted on the right front wheel to generate a braking force, and the second microcomputer 124 transmits an electric signal such that the RL controller 133 causes the EMB mounted on the left rear wheel to generate a braking force. The FR controller 132 and the RL controller 133 that receive the signals control the EMB to provide braking force to the right front wheel and the left rear wheel.

The central ECU 120 receives a wake signal from the wake sensor 118. Here, the wake-up signal refers to a door open signal, a brake light signal, an ignition signal, or the like.

The central ECU 120 that receives at least one of the door open signal, the lamp signal, and the ignition signal from the wake sensor 118 activates the wheel ECU 130 using vehicle-mounted communication. For example, when the central ECU 120 receives the lamp signal, the central ECU 120 activates the wheel ECU 130 using CAN communication.

According to one embodiment of the present disclosure, wake sensor 118 is not directly connected to wheel ECU 130 but is connected to central ECU 120. When the wake sensor 118 detects movement of the driver, for example, when the driver moves for boarding, the wake sensor 118 transmits a wake signal to the central ECU 120. The central ECU 120 that received the wake signal switches from the sleep mode to the wake mode. Thereafter, the central ECU 120 activates the wheel ECU 130 using vehicle-mounted communication, such as CAN communication.

When the circuit is designed in such a manner that the central ECU 120 activates the wheel ECU unit 130 using vehicle-mounted communication, the wheel ECU 130 need not separately include a connector pin for receiving a wake signal from the wake sensor 118. Accordingly, in the wheel ECU 130 according to one embodiment of the present disclosure, the number of connector pins is reduced as compared to a conventional wheel ECU. When the number of connector pins is reduced, there is an advantage in that, when the EMB is designed, the layout is simplified and the size of the EMB is reduced.

Wheel ECU 130 includes FL controller 131, FR controller 132, RL controller 133, and RR controller 134.

The wheel ECU 130 is mounted on a gear box or a motor. More specifically, the FL controller 131 is mounted on a motor or gear box provided on a first wheel brake FL of the left front wheel, the FR controller 132 is mounted on a motor or gear box provided on a second wheel brake FR of the right front wheel, the RL controller 133 is mounted on a motor or gear box provided on a third wheel brake RL of the left rear wheel, and the RR controller 134 is mounted on a motor or gear box provided on a fourth wheel brake RR of the right rear wheel.

The wheel ECU 130 receives electric power from the plurality of batteries 160. Specifically, FL controller 131 receives power from first battery 162, FR controller 132 receives power from second battery 164, RL controller 133 receives power from second battery 164, and RR controller 134 receives power from first battery 162.

The reason why the wheel ECU 130 receives electric power from each of the plurality of batteries 160 is to ensure redundancy when any one of the plurality of batteries 160, for example, the first battery 162, fails. In other words, even when the first battery 162 fails and the FL controller 131 is not operating, the FR controller 132 receives electric power from the second battery 164 and generates braking force at the right front wheel to brake the vehicle. Here, redundancy means that even when the first battery 162 fails and the FL controller 131 is not operated, the FR controller 132 connected to the second battery 164 can be operated to brake the vehicle, thereby ensuring the braking stability of the vehicle.

When a signal is received from the central ECU 120 using communication, for example, CAN communication, the wheel ECU 130 according to one embodiment of the present disclosure switches from the sleep mode to the wake mode.

According to one embodiment of the present disclosure, the EMB is not initialized at a point of time when the sleep mode is switched to the wake mode, but at a point of time when the driver lifts his/her foot off the brake pedal (i.e., at a point of time when the piston is retracted to release the braking force). Therefore, the wheel ECU 130 that has switched to the wake mode does not perform control for initializing the EMB before the driver lifts his/her foot off the brake pedal.

It is common for a driver to turn on the igniter switch while depressing the brake pedal and then start the vehicle while slowly lifting his/her foot off the brake pedal. When the EMB is initialized at the point of time when the driver depresses the brake pedal, the time to generate the braking force is delayed as much as required to initialize the EMB before the EMB generates the braking force. On the other hand, when the EMB is not initialized at the time point when the brake pedal is depressed, but is initialized at the time point when the braking force is released to start the vehicle after the ignition is turned on, a delay time of the EMB does not occur at the time point when the brake is depressed.

That is, when the EMB is not initialized during the wheel ECU switching to the wake mode but initialized during the braking force release, there is an effect of preventing a delay due to the initialization of the EMB when the wheel ECU switches to the wake mode.

The brake unit 140 includes a motor (not shown), a gear case (not shown), a piston (not shown), a brake pad (not shown), a caliper housing (not shown), and a caliper body (not shown).

In addition, the brake unit 140 includes a front wheel brake unit (not shown) that generates braking force in the front wheels and a rear wheel brake unit (not shown) that generates braking force in the rear wheels.

When current flows into the motor, the motor rotates forward or backward to generate a rotational force. The rotational force of the motor is transmitted to a screw (not shown) of the gear case to generate braking force.

The gear box includes a plurality of gears and screws that allow a spindle (not shown) to be linearly moved by a rotational force of a motor. When the main shaft of the gear box is linearly moved, a piston attached to one end of the caliper body is moved forward or backward, and thus, a brake pad connected to the piston presses a disc (not shown) to generate braking force.

Typical configurations related to driving of the gear box in the present disclosure are techniques that are obvious to those of ordinary skill in the art, and thus illustration and description thereof will be omitted.

Although the electromechanical brake apparatus 100 described in the present disclosure has been developed as an Electronic Parking Brake (EPB), in recent years, as the electromechanical brake apparatus 100 has been used for a main brake by replacing a conventional hydraulic brake, its range of use has been expanded. Although it is common to integrate the parking function into the EMB, in one embodiment of the present disclosure, the electromechanical brake device 100 includes a foundation brake having no parking function and a brake having a parking function.

The plurality of wheel brake units 150 includes a first wheel brake FL mounted on the left front wheel, a second wheel brake FR mounted on the right front wheel, a third wheel brake RL mounted on the left rear wheel, and a fourth wheel brake RR mounted on the right rear wheel.

In the detailed description of the present disclosure, the front wheel brake refers to the first wheel brake FL and the second wheel brake FR, and the rear wheel brake refers to the third wheel brake RL and the fourth wheel brake RR. The plurality of wheels includes all of a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel. A plurality of wheels are rotatably mounted on the vehicle body and receive braking forces from the plurality of wheel brake units 150.

The plurality of batteries 160 includes a first battery 162 and a second battery 164.

The first battery 162 supplies power to the central ECU 120, the FL controller 131, and the RR controller 134, and the second battery 164 supplies power to the central ECU 120, the FR controller 132, and the RL controller 133. The first and second batteries 162, 164 may be 12V low voltage batteries for the braking system.

When any one of the plurality of batteries 160 fails and power is not supplied to the first microcomputer 122 or the second microcomputer 124 of the central ECU 120, the wheel ECU 130 is controlled by the microcomputer that normally receives power.

Fig. 3 is a flowchart showing an algorithm of the central ECU according to an embodiment of the present disclosure.

Referring to fig. 3, in order to switch the central ECU in the sleep mode from the sleep mode to the wake mode, it is determined whether the driver gets on the vehicle (S310). For example, wake-up sensor 118 detects whether the driver is getting on the vehicle before turning on the ignition. When the wake sensor 118 detects that the driver is getting on, the wake sensor 118 transmits a door opening signal to the central ECU 120. Additionally, according to another embodiment of the present disclosure, wake-up sensor 118 includes at least one of a door open sensor, an ignition sensor, and a BLS, and upon receiving at least one of a door open signal, an ignition signal, and a brake light signal, central ECU 120 determines that the driver is getting on the vehicle.

When the driver is not getting on, the central ECU 120 continues to maintain the sleep mode until a wake signal is received from the wake sensor 118.

Meanwhile, when it is determined that the driver gets on the vehicle, for example, when at least one of the door opening signal, the brake light signal, and the ignition signal is received, the central ECU 120 switches from the sleep mode to the wake mode (S320).

Next, the central ECU 120 activates the wheel ECU 130 using the vehicle-mounted communication (S330). Here, the in-vehicle communication is, for example, CAN communication for transmitting a signal.

After the wheel ECU 130 switches to the wake mode, the central ECU 120 determines whether a brake input is input to the vehicle (S340). When the driver gets on the vehicle, the driver first depresses the brake pedal to turn on the igniter. Thus, even before the driver turns on the ignition, the central ECU 120 in the wake mode can determine whether a brake input is required based on whether the brake pedal is depressed. In the case where the driver gets on from the passenger seat side instead of the driver seat side, even when the door opening sensor cannot detect that the driver gets on, and thus the central ECU 120 is in the sleep mode, when the brake pedal is depressed before the ignition is turned on, the BLS may transmit a brake light signal to the central ECU 120 so that the central ECU 120 may be switched to the wake mode. When the central ECU 120 is switched to the wake mode, the central ECU 120 detects a brake input of the driver.

When the central ECU 120 detects a braking input, the central ECU 120 may supply current to a motor installed in the electromechanical brake apparatus 100 using current control to generate braking force.

When it has been determined that a brake input is input to the vehicle, the central ECU 120 performs comparison of the required braking force required for the driver to depress the brake pedal with the magnitude of the parking braking force generated in the wheels (S350).

When it has been determined that the parking braking force is not greater than the required braking force, since a greater braking force, that is, the required braking force, should be generated, the central ECU 120 transmits a signal to the wheel ECU 130 such that EPB is released and EMB generates the required braking force (S352). When the vehicle is parked on a slope, for example, when the parking braking force is 10kN and the braking force required for the driver to depress the brake pedal is 12kN, the central ECU 120 releases the parking braking force and further generates a braking force of 2 kN. Since the EMB of one embodiment of the present disclosure may not be a brake device provided separately from the EPB and the function of the EMB may include the function of the EBP, even if the EPB releases the parking brake force, the brake force does not become 0kN, but the brake force of 10kN is continuously maintained. Therefore, EMB only needs to generate a braking force of 2kN again.

On the other hand, when it has been determined that the required braking force is not greater than the parking braking force, since a greater braking force, that is, a braking force greater than or equal to the parking braking force should be generated in the vehicle, the central ECU 120 transmits a signal to the wheel ECU 130 such that EPB is released, and EMB maintains the generated braking force (S354).

According to one embodiment of the present disclosure, in operation S352 or S354, the wheel ECU 130 performs current control to generate or maintain a required braking force in the vehicle. Here, the wheel ECU 130 performs current control without initializing the EMB.

When the wheel ECU 130 performs current control to generate braking force without initializing EMB, the central ECU 120 cannot accurately estimate braking force generated in the vehicle due to an error in the current signal. Therefore, the braking force generated in the vehicle does not match the braking force required by the driver. However, unlike the state in which the vehicle is traveling, the braking force required before the driver turns on the igniter does not require an accurate braking force. In other words, since it is not necessary to generate an accurate braking force in the vehicle, even if there is a difference between the braking force required by the driver and the braking force generated in the vehicle, it is sufficient to keep the vehicle in a stopped state.

Thereafter, the central ECU 120 determines whether the required braking force is reduced (S360).

When the driver turns on the igniter, the driver should slowly lift the foot off the brake pedal to start the vehicle. When the driver starts to lift his/her foot off the brake pedal, the strength of the driver's stroke detected by the stroke sensor 116 decreases. The central ECU 120 determines whether a friction brake release signal for releasing the braking force from the vehicle is generated by calculating the required braking force based on the reduced stroke strength.

When it has been determined that the braking force required by the driver is not reduced, the central ECU continues to perform the current control and waits until a signal indicating that the driver lifts his/her foot off the brake pedal is transmitted.

Meanwhile, when it has been determined that the braking force required by the driver decreases, the central ECU 120 determines to release the braking force, switches the current control to the position control, and initializes the EMB (S370).

When the driver starts to lift his/her foot off the brake pedal, the piston mounted on the EMB starts to retract as the required braking force decreases.

Unlike the case of the parking state, the central ECU 120 should generate a braking force that matches the braking force required by the driver when the vehicle is in the running state. Thus, the central ECU 120 should accurately measure the position of the contact point between the brake pads and the disc by performing the EMB initialization process before the vehicle starts. The central ECU 120 adjusts the gap between the brake pads and the disc based on the measured position of the contact point. Thus, in one embodiment of the present disclosure, when the braking force is released to start the vehicle, the initialization of the EMB that is not performed in operation S352 or S354 is performed.

Since operations S330, S340 and S350 are performed almost simultaneously, when the initialization of the EMB is performed in operation S352 or S354, that is, when the wheel ECU 130 is switched to the wake-up mode and the initialization of the EMB is also performed, the time to wake up the wheel ECU 130 is delayed, and a delay occurs when the braking force is generated or maintained in operation S352 or S354. Accordingly, in one embodiment of the present disclosure, by performing the initialization of the EMB in operation S370, there is an effect of simplifying and minimizing the initialization of the EMB such that a delay time does not occur when the EMB generates a braking force after the central ECU 120 activates the wheel ECU 130 using the vehicle-mounted communication.

That is, since the vehicle is in the parking state and the initialization of the EMB is not performed in operation S352 or S354, there is no great problem in maintaining the vehicle in the stopped state even if the EMB does not generate the accurate braking force required by the driver, and thus the initialization of the EMB is performed in operation S370.

In addition, the process of switching the current control to the position control has an effect of preventing the motor from overheating. When the holding time of the clamping force is increased by continuously performing the current control, the current consumed in the motor is continuously increased so that overheating occurs. Thus, the current control is switched to the position control.

After the current control is switched to the position control, when the braking force required for the vehicle changes, for example, when the driver slowly lifts his/her foot off the brake pedal, the central ECU 120 controls the required braking force based on the change in the stroke strength detected by the stroke sensor 116. For example, when the current control is switched to the position control, when the displacement by which the piston of the EMB needs to retract based on the detected change in stroke strength is calculated to be 0.1mm, the displacements of the FL piston and the FR piston are different, respectively 0.8mm and 0.9mm. However, irrespective of the different displacements of the piston, it is sufficient that the amount of change required to move the displacement corresponds to +0.1mm. For example, in this case, the displacement of the FL piston is changed from 0.8mm to 0.9mm, and the displacement of the FR piston is changed from 0.9mm to 0.8mm.

Meanwhile, when the current control is switched to the position control, the EMB maintains the clamping force generated during the current control. When a component configured to hold a clamping force, for example, a ball screw, in the EMB is tightened, that is, a clamping force is further generated, the clamping force is represented by formula 1, and when a screw is loosened, that is, when the clamping force is released, the clamping force is represented by formula 2.

[ formula 1]

P＝Q×tan(ρ+λ)

[ formula 2]

P′＝Q×tan(ρ-λ)

Here, P represents torque when screwing the screw, P' represents rotational force when unscrewing the screw, Q represents axial force, ρ represents friction angle, and λ represents screw angle.

Meanwhile, the rotation torque when screwing down the screw is represented by formula 3, and the rotation torque when unscrewing the screw is represented by formula 4.

[ formula 3]

[ equation 4]

Here, T represents a rotational torque when screwing the screw, T 'represents a rotational torque when unscrewing the screw, P represents a rotational force calculated in formula 1, P' represents a rotational force calculated in formula 2, and de represents an effective diameter of the screw.

The difference between the rotational force and rotational torque when screwing the screw and the rotational force and rotational torque when unscrewing the screw is due to the difference between the increase and decrease of the screw angle. That is, when the screw is tightened, the rotational force and torque are large, and when the screw is loosened, the rotational force and torque are small.

Therefore, in order to generate the clamping force, a large rotational torque is required since the screw should be tightened, and in order to maintain the clamping force, no additional force is required to generate the rotational torque since only sufficient rotational torque is required to prevent the screw from loosening while maintaining the clamping force.

Therefore, when the current control is continuously maintained in operation S370, the current is continuously consumed, but when the current control is switched to the position control, since only the clamping force that has been generated needs to be maintained, there is an effect of reducing the required rotation torque and reducing the current consumption.

As described above, according to the present embodiment, in the center ECU, when a door opening signal, a brake light signal, an ignition signal, or the like is applied to the center ECU, and the center ECU activates the wheel ECU using vehicle-mounted communication, there is an effect of reducing the number of connector pins and simplifying the connection structure.

Further, according to the present embodiment, the center ECU activates the wheel ECU using vehicle-mounted communication so as to have the effect of simplifying initialization of the wheel ECU and the actuators of the EMB and minimizing the time required for the initialization so that no delay occurs in generating braking force by the EMB.

Various embodiments of the systems and techniques described here can be implemented with digital electronic circuitry, integrated circuitry, field programmable gate arrays (Field Programmable Gate Array, FPGA), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), computer hardware, firmware, software, and/or combinations thereof. Various embodiments may include implementations of one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor, which may be a special purpose processor or a general purpose processor, coupled to receive data and instructions from, and to transmit data and instructions to, the storage system, at least one input device, and at least one output device. A computer program (also referred to as a program, software application, or code) includes instructions for a programmable processor and instructions stored in a "computer-readable recording medium".

The computer-readable recording medium may include all types of storage devices that can store computer-readable data. The computer readable recording medium may be a nonvolatile or non-transitory medium such as Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), compact Disc ROM (CD-ROM), magnetic tape, floppy disk, or optical data storage device. In addition, the computer-readable recording medium may also include a temporary medium such as a data transmission medium. Furthermore, the computer-readable recording medium may be distributed over computer systems connected through a network, and the computer-readable program code may be stored and executed in a distributed manner.

Various embodiments of the systems and techniques described here can be implemented by a programmable computer. Here, the computer includes a programmable processor, a data storage system (including volatile memory, non-volatile memory, another type of storage system, or a combination thereof), and at least one communication interface. For example, the programmable computer may be one of a server, a network device, a set-top box, an embedded device, a computer expansion module, a personal computer, a notebook computer, a personal data assistant (Personal Data Assistant, PDA), a cloud computing system, and a mobile device.

Although the exemplary embodiments of the present disclosure have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed. Accordingly, for brevity and clarity, exemplary embodiments of the present disclosure have been described. The scope of the technical idea of the present embodiment is not limited by the description. Accordingly, it will be understood by those of ordinary skill that the scope of the claimed invention is not limited by the embodiments explicitly described above, but is instead limited by the claims and their equivalents.

Claims

1. A method of controlling an electromechanical braking device, the method comprising:

a central electronic control unit wake-up operation for switching the central electronic control unit to a wake-up mode based on a wake-up signal received from a wake-up sensor;

a wheel electronic control unit wakes up to operate, and the wheel electronic control unit is switched from a sleep mode to the wake-up mode by using a vehicle-mounted communication transmission signal;

a current control operation of supplying current to a motor mounted on the electromechanical brake using current control to generate braking force when a braking input is detected;

a comparison operation of comparing the magnitude of the parking braking force with the required braking force based on the braking input;

a braking force generation operation of controlling the wheel electronic control unit to release the parking braking force and the electromechanical brake to generate the required braking force when the parking braking force is determined to be less than the required braking force, and to release the parking braking force and to maintain the braking force generated by the wheels when the parking braking force is determined to be greater than or equal to the required braking force;

a position control operation of switching the current control to a position control when the braking force reaches the required braking force or the braking force is maintained; and

an initialization operation of recognizing a contact point between a brake pad and a disc when a piston mounted on the electromechanical brake is retracted when a braking force release signal is transmitted, and initializing the electromechanical brake.

2. The method of claim 1, wherein the in-vehicle communication is any one of a controller area network, CAN, communication or a local area network, LAN, communication.

3. The method of claim 1, wherein the wake-up signal is a door open signal generated by a door open sensor.

4. The method of claim 1, wherein the wake-up signal is a brake light signal generated by a brake light sensor BLS.

5. The method of claim 1, wherein the wake-up signal is an ignition signal generated by an ignition sensor.

6. The method of claim 1, wherein the braking force release signal is generated based on stroke information transmitted by a stroke sensor, and

the initializing operation includes, when the braking force release signal is received, releasing the braking force and adjusting a gap between the disc and the brake pad based on the contact point.

7. An electromechanical braking device for a vehicle, comprising:

an electromechanical brake EMB comprising an electric motor and a plurality of wheel braking units for braking the front and rear wheels;

a sensor unit including a wake-up sensor for detecting whether a driver gets on a vehicle and detecting a brake input of the driver;

a central electronic control unit ECU for switching from a sleep mode to an awake mode based on an awake signal generated by the awake sensor and calculating a required braking force based on the braking input;

a wheel ECU for switching from the sleep mode to the wake mode and controlling the EMB to generate the required braking force when the central electronic control unit ECU transmits a signal using vehicle-mounted communication; and

one or more batteries for powering the wheel ECU and the central electronic control unit ECU;

wherein the electromechanical brake apparatus for a vehicle is configured to execute the control method of the electromechanical brake apparatus according to claim 1.

8. The electromechanical braking device of claim 7, wherein the wake-up sensor comprises at least one of a door open sensor, a brake light sensor BLS, or an ignition sensor, and

the central electronic control unit ECU is switched to the wake-up mode when the central electronic control unit ECU receives at least one of a door opening signal, a brake light signal or an ignition signal generated by the wake-up sensor.